1. Field of the Invention
The present invention relates to a device substrate and a production method therefor, and electronic element and a production method therefor, an optical device and a production method therefor, and electronic apparatus. The device substrate includes, in an optical device having a multilayer structure laminated on a substrate, a film having a phase separation structure arranged previously on the substrate. The film serves as a layer to reflect light traveling in a thickness direction of the device so as to travel only in desired one direction. The device substrate according to the present invention can be appropriately used as a substrate to carry an optical device such as an electroluminescence device (EL device).
2. Description of Related Art
The related art includes devices having an optical reflection mechanism including, for example, semiconductor devices for laser, reflective liquid crystal devices, and EL devices. Such devices use a structure including a single-layer film or multilayer film so as to reflect light traveling in the devices efficiently. In addition, the following publications show that such devices can have further improved optical capabilities by arranging a film, having a high reflectance, in an appropriate position in the devices.
(1) As the semiconductor devices for laser, an example which constitutes a surface emitting semiconductor laser can be found in Japanese Patent Application No. 2002-157241. A layer necessary for at least exhibiting desired functions as a semiconductor device is referred to as a “function layer” and refers to, for example, at least an upper mirror, a lower mirrors, and a semiconductor layer structure sandwiched between these mirror layers when the device exhibits functions as the aforementioned surface emitting laser. The upper and lower mirrors herein serve as a reflector against laser light generated in the semiconductor layer structure and constitute a resonator.
The upper and lower mirrors having such a reflection function are distributed Bragg reflector (DBR) mirrors formed by laminating about 20 to 30 pairs of, for example, two AlxGa1-a. As layers having different compositions in alternate order are formed by a vacuum process, for example, using a molecular beam epitaxy method (MBE method).
(2) As the reflective liquid crystal devices, an example applied to a reflective color filter can be found in Japanese Unexamined Patent Application Publication No. 10-115704. The reflective film described in the publication has a configuration of a multilayer interference film including a multilayer assemblage of a thin film comprising a high refractive index material and a thin film including a low refractive index material alternately laminated on a substrate. Specifically, the reflective film described in the embodiment thereof is a multilayer interference film prepared by laminating silicon dioxide (SiO2: refractive index 1.461) and titanium dioxide (TiO2: refractive index 2.495) alternately by using, for example, as electron beam (EB) deposition method.
(3) As the reflective film for use in EL devices, detailed description thereof can be found in, for example, Japanese Unexamined Patent Application Publication No. 2001-52861. Such EL devices have a fundamental configuration including a substrate, and a first electrode, a layer contributing to light emission (light-emitting layer), and a second electrode, arranged on the substrate in this order. Light generated from the light-emitting layer is emitted via the first electrode and the substrate (back emission: hereinafter briefly referred to as BE) or emitted via the second electrode (top emission: hereinafter briefly referred to as TE).
In the BE system, transparent materials are used for the substrate and the first electrode, and it is preferred that the second electrode is a reflective electrode or has a reflective film thereon to thereby increase the emission efficiency. In contrast, in the TE system, a transparent material is used for the second electrode, and it is preferred that the first electrode is a reflective electrode or a reflective film is arranged between the first electrode and the substrate to thereby increase the emission efficiency. The following materials for these transparent electrode, reflective electrode, and reflective film are listed.
Transparent electrode: Cul, ITO, SnO2, ZnO and other transparent materials
Reflective electrode: aluminum, calcium, and other metals; magnesium-silver, lithium-aluminum, and other alloys; magnesium/silver, and other multilayer films of metals, (lithium fluoride)/aluminum, and other multilayer films of an insulator and a metal
Reflection coating: known metal films
Example (1) above, discloses an example in which the device configuration in BE and an Al electrode as the second electrode continuing a reflective electrode is formed by vapor deposition.
As described in (1) to (3) above, the reflective layers used in related art devices having an optical reflection mechanism must be prepared by a preparation method using a vacuum process. Device for use in this preparation method is expensive, operates at high cost and requires a large space for the arrangement thereof. Accordingly, the production cost of the reflective films is reduced to an only limited extent.
In addition, many of reflective layers including a single-layer film may not sufficiently satisfy the optimum reflection conditions for the devices. Consequently, a structure including a multilayer film is widely used. However, this complicates the production process of the reflective layer, thus inviting high cost of the devices.